This invention relates in general to battery monitoring devices and, in particular, to a sensor for monitoring the level of the electrolyte in a wet cell battery.
At high charge rates, a portion of the water in the electrolyte of a lead-acid storage cell is lost by electrolysis. If, as a result of this loss and losses by other mechanisms such as evaporation, the electrolyte level drops so low as to expose the surface of the cell electrodes, the cell may be quickly and permanently damaged. On the other hand, if a cell is overwatered prior to the charging of the battery, the electrolyte may overflow during or following charging with deleterious consequences.
Accurate and reliable information about electrolyte level is particularly valuable in cases where high-capacity, many cell battery system provide operating or emergency power such as is the case in a submarine battery system. Typically, the electrolyte level in such systems is monitored by periodic visual inspection of randomly selected cells (if the battery jar is transparent) or by opening the cells and inserting a dip tube to determine the liquid level. Obviously, this approach is of limited effectiveness in detecting problems and is also time consuming. Often the batteries are located in inaccessible areas further complicating the manual monitoring level.
Many methods have been proposed to monitor the level of the electrolyte in a wet cell battery. Generally, these prior methods generate a signal when the liquid in a cell falls below, or rises to, a predetermined level. However, a simple, reliable, and accurate sensor for indicating the instantaneous liquid level which is capable of transmitting the data to a remote location is highly desirable. The present invention is intended to provide such a sensor.